Update IAM.1.07_shared_account_restrictions.html.md

Why is this change being made?

Added policy ref links and formatted the page

Does this MR meet the acceptance criteria? Yes

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what